Chapter 11 Potentiometer & LED
We have learned how to use ADC and DAC before. When using DAC output analog to drive LED, we found that, when the output voltage is less than led turn-on voltage, the LED does not light; when the output analog voltage is greater than the LED voltage, the LED lights. This leads to a certain degree of waste of resources. Therefore, in the control of LED brightness, we should choose a more reasonable way of PWM control. In this chapter, we learn to control the brightness of LED through a potentiometer.
Project 11.1 Soft Light
In this project, we will make a soft light. We will use an ADC Module to read ADC values of a potentiometer and map it to duty cycle of the PWM used to control the brightness of a LED. Then you can change the brightness of a LED by adjusting the potentiometer.
Component List
ESP32-WROVER x1
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GPIO Extension Board x1
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Breadboard x1
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LED x1
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Resistor 220Ω x1
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Jumper M/M x5
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Rotary potentiometer x1
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Circuit
Schematic diagram |
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Hardware connection |
If you need any support, please contact us via: support@freenove.com
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Sketch
Sketch_11.1_Softlight
Download the code to ESP32-WROVER, by turning the adjustable resistor to change the input voltage of GPIO25, ESP32 changes the output voltage of GPIO4 according to this voltage value, thus changing the brightness of the LED.
The following is the code:
1/**********************************************************************
2 Filename : SoftLight
3 Description : Controlling the brightness of LED by potentiometer.
4 Auther : www.freenove.com
5 Modification: 2024/06/18
6**********************************************************************/
7#define PIN_ANALOG_IN 4
8#define PIN_LED 25
9#define CHAN 0
10void setup() {
11 ledcAttachChannel(PIN_LED, 1000, 12, CHAN);
12}
13
14void loop() {
15 int adcVal = analogRead(PIN_ANALOG_IN); //read adc
16 int pwmVal = adcVal; // adcVal re-map to pwmVal
17 ledcWrite(PIN_LED, pwmVal); // set the pulse width.
18 delay(10);
19}
In the code, read the ADC value of potentiometer and map it to the duty cycle of PWM to control LED brightness.
Project 11.2 Soft Colorful Light
In this project, 3 potentiometers are used to control the RGB LED and in principle it is the same as the Soft Light project. Namely, read the voltage value of the potentiometer and then convert it to PWM used to control LED brightness. Difference is that the original project only controlled one LED, but this project required (3) RGB LEDs.
ESP32-WROVER x1
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GPIO Extension Board x1
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Breadboard x1
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RGBLED x1
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Resistor 220Ω x3
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Jumper M/M x13
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Rotary potentiometer x3
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Circuit
Schematic diagram |
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Hardware connection |
If you need any support, please contact us via: support@freenove.com
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Sketch
Sketch_11.2_SoftColorfulLight
Download the code to ESP32-WROVER, rotate one of the potentiometers, then the color of RGB LED will change.
The following is the program code:
1/**********************************************************************
2 Filename : SoftColorfulLight
3 Description : Controlling the color of RGBLED by potentiometer.
4 Auther : www.freenove.com
5 Modification: 2024/06/18
6**********************************************************************/
7const byte ledPins[] = {15, 2, 4}; //define led pins
8const byte pwmChns[] = {0, 1, 2}; //define the pwm channels
9const byte adcChns[] = {13, 12, 14}; // define the adc channels
10int colors[] = {0, 0, 0}; // red, green ,blue values of color.
11void setup() {
12 for (int i = 0; i < 3; i++) { //setup the pwm channels
13 ledcAttachChannel(ledPins[i], 1000, 8, pwmChns[i]);
14 }
15}
16
17void loop() {
18 for (int i = 0; i < 3; i++) {
19 colors[i] = map(analogRead(adcChns[i]), 0, 4096, 0, 255); //calculate color value.
20 ledcWrite(ledPins[i], 256 - colors[i]); //set color
21 }
22 delay(10);
23}
In the code you can read the ADC values of the 3 potentiometers and map it into a PWM duty cycle to control the 3 LED elements to vary the color of their respective RGB LED.
Project 11.3 Soft Rainbow Light
In this project, we use potentiometer to control Freenove 8 RGB LED Module.
Component List
ESP32-WROVER x1
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GPIO Extension Board x1
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Breadboard x1
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Freenove 8 RGB LED Module x1
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Jumper F/M x3 Jumper M/M x3 |
Sketch
Sketch_11.3_Soft_Rainbow_Light
Download the code to ESP32-WROVER, rotate the handle of the potentiometer, and the color of the lamp ring will change.
If you need any support, please feel free to contact us via: support@freenove.com
The following is the program code:
1/**********************************************************************
2 Filename : SoftRainbowLight
3 Description : Make the strip light up in rainbow colors.
4 Auther : www.freenove.com
5 Modification: 2024/06/18
6**********************************************************************/
7#include "Freenove_WS2812_Lib_for_ESP32.h"
8
9#define PIN_POT 13 // Define analog input pins
10#define LEDS_COUNT 8 // The number of led
11#define LEDS_PIN 2 // define the pin connected to the Freenove 8 led strip
12#define CHANNEL 0 // RMT module channel
13#define BRIGHTNESS 100 // breghtness, the value range is 0-255.
14Freenove_ESP32_WS2812 strip = Freenove_ESP32_WS2812(LEDS_COUNT, LEDS_PIN, CHANNEL, TYPE_GRB);
15
16void setup() {
17 strip.setBrightness(BRIGHTNESS);
18 strip.begin();
19}
20
21void loop() {
22 int colorPos = map(analogRead(PIN_POT), 0, 4095, 0, 255);
23 for (int i = 0; i < LEDS_COUNT; i++) {
24 strip.setLedColorData(i,strip.Wheel(colorPos + i * 255 / 8)); // Set color data.
25 }
26 strip.show(); // Send color data to LED, and display.
27 delay(10);
28}
The overall logical structure of the code is the same as the previous project rainbow light, except that the starting point of the color in this code is controlled by potentiometer.